Refining molten metals



Patented July 28, 1931 UNITED STATES PATENT OFFICE GEORGE S. EVANS, OF'BRONXVILLE, NEW YORK, ASSIGNOB. TO THE MATHIESON ALKALI WORKS, INC., OFNEW YORK, 1\T.'Y., A CORPORATION OF NEW YORK BEFINING MOLTEN METALS NoDrawing.

This invention relates to improvements in the refining of molten metals.The invention is of special value and application in connection with therefining of ferrous met- }5 als with soda ash refining agents, but it isalso 'useful in connection with the refining of other metals and inconnection with the use of other refining agents.

Refining agents fusible at the temperature of the molten metal and ofdensity less than that of the molten metal, such as the soda ashrefining agents described in Letters Patent Nos. 1,590,730 and1,590,739, issued on applications filed by me, may be used withadvantage in refining slags in furnace, forehearth or ladle operations,but as hitherto applied such refining agents have not been as effectiveas might be expected because of limitations of the period or extent ofcontact between the refining agent and the molten metal. This inventionprovides an improved method of applying such refining agents which makespossible more intimate contact between the refining agent andthe moltenmetal as well as prolongation of the period of contact, or progressivecontact, 'between the refining agent and the molten metal. In some casesthis improvement makes such refining agents of broader application andin other cases this improvement-makes possible important economy in theuse of such refining agents.

1 According to the present invention, the molten metal to be refined isrun into a refining receptacle onto a preformed matte of the metal andthe refining agent so that the refining agent is progressively releasedfrom this preformed matte to rise through the metal bath in intimatecontact with the molten metal as the matte is heated by the moltenmetal.The progressive release of the grefiningagent prolongs the period ofcontact and intimate contact is promoted not only by the travel of thereleased refining agent through the metal bath, but also by the motionin the metal bath induced by this travel. The tween the metal of thematte and the added molten metal, as well as the difference in 60composition of the two, also tends to induce perature of the metal-bathin.

may be formed by adding difference in temperature be'- Application filedOctober 18, 1929. Serial No. 400,743.

motion in the metal bath. The operation may be carried out in a unifiedmanner by forming a matte of the refining agent with an initial orprimary charge of the molten metal in the refining receptacle and byrunning a secondary or major charge of the molten metal into therefining receptacle onto this thus formed matte, or the operation may becarried out upon continuously successive batches of molten metal byforming a matte with the refining agent and a portion of the moltenmetal from a preceding batch held in the refining receptable and runningthe molten metal into the refining receptacle onto this thus formedmatte. The period of operation, and the rate at which the refining agentis released, can be controlled within limits by regulating the ratiobetween the weight of metal in the matte and the weight of metal runonto the preformed mattein the refining operation, the period beingprolonged by increasing this ratio. The period of the operation can alsobe controlled within limits by regulating the temperature of the mattewhen the molten metal is run into the refining receptacle onto thematte. In generalthe matte should be permitted to 0001 only to atemperature low enough to retain, mechanically, the refining agent forthe desired period as further cooling necessarily reduces the temwhichthe refining operation is carried out. The proportion of the refiningagent used may generally be reduced as compared to similar operations inwhich the refining agent is added to the surface of a metal bath or inwhich the refining agent is placed as such in the refining receptacleinto which the molten metal is run.

In refining ferrous metals with fused, briquetted or sintered, soda ash,the matte soda ash per 100-200 pounds of molten metal and allowing themixture to freeze and from20-25 times the weight of metal contained inthe matte may then be run onto the matte, for example. In refiningcopper with fused, briquetted or sintered soda ash,

the matte may be formed by adding 5-10 2-20 pounds of may be securedwith pounds of soda ash per 100-200 pounds of metal and allowing thismixture to freeze and from 20-25 times the metal content in the mattemay then be run onto the matte, for example. The refining agent isadvantageously used in proportion to effect a maximum purification,sulphur reduction for example, per unit of refining agent with a minimumremoval of desirable elements and a minimum of injury to the lining ofthe refining receptacle.

In one aspect this invention provides an improved method of applyingrefining agents such as soda ash in refining operations in which a largeweight of metal is treated per operation. Such o erations necessarilyinvolve the use of a arge refining receptacle which necessity tends toreduce the effectiveness of the refining agent used, as hithertoapplied, because of insufiicient contact, as to period or extent,between the refining agent and the metal bath. By means of thisinvention, just as intimate contact and just as prolonged contactbetween the refining agent and the metal bath a large metal bath as witha small metal bath.

It will also be apparent that the advantages of this invention many beenjoyed, in many cases, without modi cation of existing foundry orsmelter equipment and without severe change in usual routine.

I claim:

1. In refining molten metals with refining agents fusible atthe-temperature of the molten metal and of density less than that of themolten metal, the improvement which comprises running a primarycharge ofthe l molten metal into a refining receptacle and 4 the resulting metalmixture in Fi i permitting it to cool thereln in admixture with a chargeof the refining agent to a temperature at which the -refining agent ismechanically retained by the metal, and thereafter running a secondarychargeof the molten metal into the refining receptacle onto the thusformed matte, and holding the refining receptacle until the matte hasbeen heated by the addition of molten metal to a temperature at whichthe refining agent has been released.

2. In refining molten metals with refining agents fusible at thetemperature of the molten metal and of density less than that of themolten metal, the improvement which comprises running a minor charge ofthe molten metal into a refining receptacle and permitting it to cooltherein in admixture with a charge of the refining agent to atemperature at which the refining agent is mechanically retained by themetal, and thereafter running a major charge of the molten metal intothe refining receptacle I matte, and holding in the refiningonto the,thus formed the resulting metal mixture receptacle until the matte hasbeen heated by the addition of molten metal to a temperature at whichthe. refining agent has been released. i

3. In refining molten metals with refinin agents fusible atthetemperature of the molten metal and of density less than that of themolten metal, the improvement which comprises running a primary chargeof the molten metal into a refining receptacle and permitting it to coolthereln in admixture with a charge of the refining agent to atemperature at which the refimng agent is mechanically retained by themetal, and thereafter running a secondary charge of the molten metalinto the refining receptacle onto the thus formed matte.

4. In refining molten metals with soda ash refining agents, theimprovement which comprises running the molten metal into a refiningreceptacle onto a solid preformed matte of the metal and holding theresulting metal mixture in the refining receptacle while the matte isheated by the addition of molten metal to a temperature at which therefining agent is progressively released and rises through the moltenmetal.

5. Inrefining molten metals with soda ash refining agents, theimprovement which comprises running a primary charge of the molten metalinto a refining receptacle and permitting it to cool therein inadmixture with a charge of the refining agent to a temperature at whichthe refining agent is mechanically retained by the metal, and thereafterrunning a secondary charge of the molten metal into the'refiningreceptacle onto the thus formed matte.

In testimony whereof I afiix my signaand the refining agent

